New protonic conduction processes of perfluorosulfonic acid membranes by gamma-ray irradiation at a dose of up to 240kGy at room temperature in air were found by direct current resistance measurement. The conductivities of the membranes at 373 and 300K in vacuum were enhanced to approximately one and two orders of magnitude higher, respectively, than the conductivities of an unirradiated membrane. The new and original activation energies required for the conductivities in the temperature range below and above 343K were determined to be 0.12 and 0.84eV, respectively, which corresponded to the potential energy of the H diffusion due to radiation-induced defects and the existing sulfonate group. By means of ultraviolet, visible, and infrared optical absorption and by hydrogen-ion-exchange capacity measurements, it was revealed that radiation-induced defects such as fluorocarbon and peroxy radicals, and C=O bonds included in carbonyl groups were related to the new proton conduction processes. The modification of H absorption characteristics due to the radiation-induced defects in near-surface regions induces the enhancement of the proton conductivity.

Protonic Conduction Processes of Gamma-Ray-Irradiated Perfluorosulfonic Acid Membranes. B.Tsuchiya, Y.Konishi, S.Nagata, T.Shikama: Solid State Ionics, 2008, 179[21-26], 1128-32